This invention relates to anti-jackknifing devices between a tractor and a trailer and controls therefor.
Various attempts to prevent jackknifing have included the provision of apparatus and method disclosed in U.S. Pat. No. 4,700,966, whereby angular movement between a tractor and trailer is limited upon activation of an anti-jackknifing apparatus mounted beneath the trailer. That system requires the driver to manually activate and deactivate the apparatus, based upon certain audio and visual signals rendered by displays within the cab of the tractor indicating that the angle between the tractor and the trailer has exceeded a predetermined angle, as for example 15.degree.. Thus, for example, a driver would have to manually deactivate the system each time he enters a turn resulting in an angle between the tractor and the trailer exceeding the said predetermined angle so that free pivotal motion is thereafter allowed between the tractor and trailer. Such a system has been shown to have imposed an excessive amount of discretion upon the driver, who must additionally remain alert for other factors influencing the safe operation of his rig. Consequently, the anti-jackknifing apparatus may not be activated as often as conditions warrant. The apparatus described above additionally presents logistical problems, stemming from the necessity for providing corresponding electrical signaling equipment within the cabs of each tractor for every trailer having an anti-jackknifing apparatus. First, such electrical equipment would have to be supplied to every tractor of one's inventory, regardless of whether a corresponding trailer includes an anti-jackknifing apparatus. Thus, for example, assume a given number of tractors and trailers and that only some of the trailers have an anti-jackknifing apparatus. It would be necessary to provide electrical equipment to all of the tractors, even though a lesser number of trailers possess anti-jackknifing apparatus. Moreover, since trailers are frequently rented, one encounters the problem of locating a tractor having electrical equipment corresponding with the anti-jackknifing apparatus on the trailer. Given that only a small percentage of tractors would be so provided, locating such a tractor presents a significant logistical problem.
Accordingly, it is an important object of the invention to provide an anti-jackknifing apparatus which is automatically engaged upon attainment of a predetermined speed.
Another important object of the invention is to provide such apparatus which is automatically disengaged upon either a reduction of the speed of the trailer below a predetermined speed or the activation of a turning signal before making a turn.
Another important object of the invention is to equip a trailer with both a mechanical anti-jackknifing apparatus and corresponding electrical sensing and signaling means so that the entire anti-jackknifing system is located solely upon the trailer.